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1,884 Matching Results

Start Over Access Open Access Decade 1990-1999 Year 1998 Month April

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Results: 1 - 24 of 1,884 next

(open access)

Advanced Emissions Control Development Program

The objective of the Advanced Emissions Control Development Program (AECDP) is to develop practical, cost-effective strategies for reducing the emissions of air toxics from coal-fired boilers. Ideally, the project aim is to effectively control air toxic emissions through the use of conventional flue gas cleanup equipment such as electrostatic precipitators (ESPS), fabric filters (baghouse), and wet flue gas desulfurization. Development work to date has concentrated on the capture of mercury, other trace metals, fine particulate and hydrogen chloride. Following the construction and evaluation of a representative air toxics test facility in Phase I, Phase II focused on the evaluation of mercury and several other air toxics emissions. The AECDP is jointly funded by the United States Department of Energy's Federal Energy Technology Center (DOE), the Ohio Coal Development Office within the Ohio Department of Development (oCDO), and Babcock& Wilcox-a McDermott company (B&W).

Date: April 1, 1998

Creator: A.P.Evans; Redinger, K.E. & Holmes, M.J.

Object Type: Report

System: The UNT Digital Library

(open access)

GEOTHERMAL HEAT PUMP GROUTING MATERIALS

The thermal conductivity of cementitious grouts has been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. The cement-sand grouts were also tested for rheological characteristics, bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the thermal conductivity, permeability, bonding and exotherm data for selected cementitious grouts. The theoretical reduction in bore length that could be achieved with the BNL-developed cement-sand grouts is examined. Finally, the FY 98 research and field trials are discussed.

Date: April 1, 1998

Creator: ALLAN,M.

Object Type: Article

System: The UNT Digital Library

(open access)

An automated vacuum gauge calibration system

An automated system for calibrating vacuum gauges over the pressure range of 10{sup {minus}6} to 0.1 Pa was designed and constructed at the National Institute of Standards and Technology (NIST) for the Department of Energy (DOE) Primary Standards Laboratory at Sandia National Laboratories (SNL). Calculable pressures are generated by passing a known flow of gas through an orifice of known conductance. The orifice conductance is derived from dimensional measurements and accurate flows are generated using metal capillary leaks. The expanded uncertainty (k = 2) in the generated pressure is estimated to be between 1% and 4% over the calibration range. The design, calibration results. and component uncertainties will be discussed.

Date: April 1, 1998

Creator: Abbott, P. J. & Benner, M. S.

Object Type: Article

System: The UNT Digital Library

(open access)

Laser barometer

This paper describes an invention of a pressure measuring instrument which uses laser radiation to sense the pressure in an enclosed environment by means of measuring the change in refractive index of a gas - which is pressure dependent.

Date: April 1, 1998

Creator: Abercrombie, K.R.; Shiels, D. & Rash, T.

Object Type: Patent

System: The UNT Digital Library

(open access)

Abilene Philharmonic Playbill: April 18-May 2, 1998

Program for Abilene Philharmonic concerts performed on April 18th (seventh concert, classical) and May 2nd (eighth concert, classical) during the 48th season. It includes information about the pieces performed, artists and musicians, and advertising from local companies.

Date: April 1998

Creator: Abilene Philharmonic

Object Type: Book

System: The Portal to Texas History

(open access)

Global Climate Change: Selected Legal Questions About the Kyoto Protocol

This report discusses the Kyoto Protocol and whether the United States is now legally bound by the Protocol, the legal implications of signing it, whether it could be implemented as an executive agreement without submission to the Senate, and whether the Protocol could be used as the legal basis for regulation of emissions even prior to ratification.

Date: April 10, 1998

Creator: Ackerman, David M.

Object Type: Report

System: The UNT Digital Library

(open access)

The Law of Church and State: The Proposed Religious Freedom Amendment, H.J. Res. 78

This report summarizes legislative developments on the proposal and briefly analyzes its likely legal effect if added to the Constitution.

Date: April 20, 1998

Creator: Ackerman, David M.

Object Type: Report

System: The UNT Digital Library

(open access)

Waste form development and characterization in pyrometallurgical treatment of spent nuclear fuel.

Electrometallurgical treatment is a compact, inexpensive method that is being developed at Argonne National Laboratory to deal with spent nuclear fuel, primarily metallic and oxide fuels. In this method, metallic nuclear fuel constituents are electrorefined in a molten salt to separate uranium from the rest of the spent fuel. Oxide and other fuels are subjected to appropriate head end steps to convert them to metallic form prior to electrorefining. The treatment process generates two kinds of high-level waste--a metallic and a ceramic waste. Isolation of these wastes has been developed as an integral part of the process. The wastes arise directly from the electrorefiner, and waste streams do not contain large quantities of solvent or other process fluids. Consequently, waste volumes are small and waste isolation processes can be compact and rapid. This paper briefly summarizes waste isolation processes then describes development and characterization of the two waste forms in more detail.

Date: April 16, 1998

Creator: Ackerman, J.

Object Type: Article

System: The UNT Digital Library

(open access)

Improved photon production data for MCNP{trademark}

Computer simulations with MCNP are often used to obtain information from measurements of neutron induced gamma-ray spectra. For such simulations to be useful, the complicated spectra produced by a wide variety of nuclides must be reproduced, requiring high quality nuclear data. A previous assessment of the neutron induced photon production data in the MCNP data libraries indicated a need for improvement. The photon production data were often based on outdated experiments and binned in such wide energy groups as to be of limited value for some applications. This paper describes the work that is underway at Los Alamos National Laboratory to improve the photon production data for thermal neutron capture reactions. To date, high quality photon production data for each stable isotope of chlorine, chromium, iron, copper, and nickel have been obtained. The improved spectra have been incorporated into ENDF formatted evaluations and processed into corresponding MCNP data files. Similar improvements for aluminum, manganese, silicon, calcium, and vanadium are also planned. The methodology used to produce the spectra is discussed, and sample results for chlorine are presented.

Date: April 1, 1998

Creator: Adams, A. A.; Frankle, S. C. & Little, R. C.

Object Type: Article

System: The UNT Digital Library

(open access)

Tank waste information network system II (TWINS2) year 2000 compliance assurance plan

The scope of this plan includes the Tank Waste Information Network System II (TWINS2) that contains the following major components: Tank Characterization Database (TCD), Tank Vapor Database (TVD), Data Source Access (DSA), automated Tank Characterization Report, Best-Basis Inventory Model (BBIM), and Tracker (corrective action tracking) function. The automated Tank Characterization Report application currently in development also will reside on-the TWINS system as will the BBIM. Critical inputs to TWINS occur from the following databases: Labcore and SACS. Output does not occur from TWINS to these two databases.

Date: April 16, 1998

Creator: Adams, M.R.

Object Type: Report

System: The UNT Digital Library

(open access)

M Theory on AdSp x 511-p and superconformal field theories

We study the large N limit of the interacting superconformal field theories associated with N M5 branes or M2 branes using the recently proposed relation between these theories and M theory on AdS spaces. We first analyze the spectrum of chiral operators of the 6d (0, 2) theory associated with M5 branes in flat space, and find full agreement with earlier results obtained using its DLCQ description as quantum mechanics on a moduli space of instantons. We then perform a similar analysis for the D{sub N} type 6d (0, 2) theories associated with M5 branes at an R{sup 5}/Z{sub 2} singularity, and for the 3d N = 8 superconformal field theories associated with M2 branes in flat space and at an R{sup 8}/Z{sub 2} singularity respectively. Little is known about these three theories, and our study yields for the first time their spectrum of chiral operators (in the large N limit).

Date: April 1, 1998

Creator: Aharony, Ofer; Yaron, Oz & Zheng, Yin

Object Type: Article

System: The UNT Digital Library

(open access)

Investigation of syngas interactions in alcohol synthesis catalyst

The primary objectives of the project are to (a) synthesize, by controlled sequential and co-impregnation techniques, three distinct composition metal clusters (consisting of Cu-Co-Cr and Cu-Fe-Zn): rich in copper (Methanol selective), rich in ferromagnetic metal (Co or Fe-Hydrocarbon selective) and intermediate range (mixed alcohol catalysts); (b) investigate the changes in the magnetic character of the systems due to interaction with CO, through Zero-field Nuclear Magnetic Resonance (ZFNMR) study of cobalt and Magnetic character (saturation magnetization and coercive field) analysis of the composite catalyst of Vibrating Sample Magnetometry (VSM); (c) examine the changes in syngas adsorption character of the catalyst as the composition changes, by FTIR Spectroscopic analysis of CO stretching frequencies; (d) determine the nature and size of these intermetallic clusters by Scanning Electron Microscopy (SEM); and (e) perform catalytic runs on selected samples and analyze the correlations between the physical and chemical characteristics. The catalysts chosen have a greater promise for industrial application than the Rh and Mo based catalysts. Several groups preparing catalysts by synthetic routes have reported divergent results for activity and selectivity. Generally the research has followed an empirical path and less effort is devoted to analyze the mechanisms and the scientific basis. The primary intent …

Date: April 15, 1998

Creator: Akundi, M. A.

Object Type: Report

System: The UNT Digital Library

$Diffractive dijet production in CDF$ (open access)

Diffractive dijet production in CDF

We have studied events with a high-x{sub F} antiproton and two central jets in CDF, with p{anti p} collisions at {radical}s = 630 and 1800 GeV. These events are expected to be dominated by diffraction (pomeron exchange). The jet E{sub T} spectra are very similar to those of non-diffractively produced jets but slightly steeper; their azimuthal difference {Delta}{phi} is more peaked at 180{degree}.

Date: April 17, 1998

Creator: Albrow, M.G.

Object Type: Article

System: The UNT Digital Library

(open access)

Fractional Brownian motion as a nonstationary process: An alternative paradigm for DNA sequences

Article discussing the fractional Brownian motion (FBM) as a nonstationary process and an alternative paradigm for DNA sequences.

Date: April 1998

Creator: Allegrini, Paolo; Buiatti, Marco, 1972-; Grigolini, Paolo & West, Bruce J.

Object Type: Article

System: The UNT Digital Library

(open access)

Integrated micro-electro-mechanical sensor development for inertial applications

Electronic sensing circuitry and micro electro mechanical sense elements can be integrated to produce inertial instruments for applications unheard of a few years ago. This paper will describe the Sandia M3EMS fabrication process, inertial instruments that have been fabricated, and the results of initial characterization tests of micro-machined accelerometers.

Date: April 1, 1998

Creator: Allen, J. J.; Kinney, R. D. & Sarsfield, J.

Object Type: Article

System: The UNT Digital Library

(open access)

R and D investment strategies for condition-based maintenance: An economic model to assist process, plant, and management in the decision making process

In today`s manufacturing environment, systems and equipment are being asked to perform at levels not thought possible a decade ago. The intent is to push process operations, product quality, and equipment reliability, availability, and maintainability to unprecedented levels while maintaining budgetary structures consistent with cost reduction initiatives. In light of this, there is a demand to reduce operational and support costs and eliminate or minimize any new capital investments in plant equipment while increasing process efficiency and revenues. In short, manufacturers are trying to invoke new measures to ensure plant performance while minimizing costs and extending operational life of new and/or aging equipment. The only way this can be accomplished is by developing new and innovating approaches in condition-based maintenance. To achieve this while adhering to strict economic constraints requires the development of new sensors, systems, and methods for interrogating, diagnosing, and controlling systems. The old adage, business as usual, will not suffice in this new way of thinking. What will be required is an investment strategy that mitigates R and D risks by developing economic indicators (operational and costs) that qualify the ability of a proposed technology to meet the functional and operational needs of a process. The strategy …

Date: April 1, 1998

Creator: Allgood, G.O.

Object Type: Article

System: The UNT Digital Library

(open access)

Image appraisal for 2D and 3D electromagnetic inversion

Linearized methods are presented for appraising image resolution and parameter accuracy in images generated with two and three dimensional non-linear electromagnetic inversion schemes. When direct matrix inversion is employed, the model resolution and model covariance matrices can be directly calculated. The columns of the model resolution matrix are shown to yield empirical estimates of the horizontal and vertical resolution throughout the imaging region. Plotting the square root of the diagonal of the model covariance matrix yields an estimate of how the estimated data noise maps into parameter error. When the conjugate gradient method is employed rather than a direct inversion technique (for example in 3D inversion), an iterative method can be applied to statistically estimate the model covariance matrix, as well as a regularization covariance matrix. The latter estimates the error in the inverted results caused by small variations in the regularization parameter. A method for calculating individual columns of the model resolution matrix using the conjugate gradient method is also developed. Examples of the image analysis techniques are provided on a synthetic cross well EM data set.

Date: April 1, 1998

Creator: Alumbaugh, D.L. & Newman, G.A.

Object Type: Article

System: The UNT Digital Library

(open access)

Southwest Retort, Volume 50, Number 17, April 1998

This publication of the Dallas-Fort Worth Section of the American Chemical Society includes information about research, prominent scientist, organizational business, and various other stories of interest to the community.

Date: April 1998

Creator: American Chemical Society. Dallas/Fort Worth Section.

Object Type: Journal/Magazine/Newsletter

System: The UNT Digital Library

(open access)

Electron transport uniformity characterization of CdZnTe using alpha particles

Novel electrode configurations, such as coplanar grids, have been successful in mitigating the effects of poor hole transport in CdZnTe gamma-ray detectors. However, poor material uniformity remains a major problem preventing the widespread application of such detectors in gamma-ray spectroscopy. Uniform electron transport is critical for achieving good gamma-ray detection performance in the coplanar-grid configuration. The authors have investigated the use of alpha-particle response as a quick and simple electron transport uniformity screening technique for material selection, and as a method to study other spectral broadening mechanisms in coplanar-grid detectors. The method consists of uniformly illuminating, with an alpha-particle source, the cathode side of the CdZnTe crystal in either a planar or a coplanar-grid detector configuration. In the planar geometry, the variation in the measured pulse heights is dictated in large part by the uniformity of the electron transport. An alpha-particle spectrum that has a single sharp peak with little background indicates uniform electron transport and, consequently, that the CdZnTe crystal should result in a coplanar-grid detector with good gamma-ray detection performance. In the coplanar geometry, the measured pulse-height variation provides information on additional sources of spectral broadening. In this paper the authors present the results of their study to …

Date: April 1, 1998

Creator: Amman, M.; Lee, J. S. & Luke, P. N.

Object Type: Report

System: The UNT Digital Library

(open access)

Application of cathodic arc deposited amorphous hard carbon films to the head/disk tribology

Amorphous hard carbon films deposited by filtered cathodic arc deposition exhibit very high hardness and elastic modulus, high mass density, low coefficient of friction, and the films are very smooth. All these properties are beneficial to applications of these films for the head/disk interface tribology. The properties of cathodic arc deposited amorphous carbon films are summarized, and they are compared to sputter deposited, hydrogenated (CH{sub x}), and nitrogenated (CN{sub x}) carbon films which are the present choice for hard disk and slider coatings. New developments in cathodic arc coaters are discussed which are of interest to the disk drive industry. Experiments on the nanotribology, mass density and hardness, corrosion behavior, and tribochemical behavior of cathodic arc films are reported. A number of applications of cathodic arc deposited films to hard disk and slider coatings are described. It is shown that their tribological performance is considerably better compared to CH{sub x} and CN{sub x} films.

Date: April 1998

Creator: Anders, S.; Bhatia, C. S.; Fong, W.; Lo, R. Y. & Bogy, D. B.

Object Type: Report

System: The UNT Digital Library

(open access)

Study of Hard Disk and Slider Surfaces Using X-Ray Photoemission Electron Microscopy and Near-Edge X-Ray Absorption Fine Structure Spectroscopy

X-ray Photo Emission Electron Microscopy (X-PEEM) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy were applied to study the properties of amorphous hard carbon overcoats on disks and sliders, and the properties of the lubricant. The modification of lubricants after performing thermal desorption studies was measured by NEXAFS, and the results are compared to the thermal desorption data. The study of lubricant degradation in wear tracks is described. Sliders were investigated before and after wear test, and the modification of the slider coating as well as the transfer of lubricant to the slider was studied. The studies show that the lubricant is altered chemically during the wear. Fluorine is removed and carboxyl groups are formed.

Date: April 1998

Creator: Anders, Simone; Stammler, Thomas; Bhatia, C. Singh; Stoehr, Joachim; Fong, Walton; Chen, Chao-Yuan et al.

Object Type: Report

System: The UNT Digital Library

(open access)

Bigplate: an oblique angle explosive EOS test

Bigplate is an advanced explosive equation of state (EOS) test. It consists of a point detonator driving a large disc (100 mm radius) of explosive, which pushes a 0.5 mm thick copper or tantalum plate. The plate is observed by a five-beam Fabry-Perot interferometer, which has beams at 0, 10, 20,40 and 80 mm on the plate. A short Fabry gives the jump-off to high accuracy; a long Fabry runs out to I0-15 microsec. A detailed error analysis is given, with the final velocity measurements considered good to ±0.066 mm/microsec. Jump-offs are measured to 0.01-0.02 microsec. Spall is seen in all shots, which creates a time delay on both the first and second velocity plateaus. A 0.1 microsec delay in jump-off of unknown origin is also seen at 80 mm. In order of decreasing explosive ideality, the explosives tired have been LX-14, LX-04 and LX-17. To partially negate the time delays, the data and code runs are overlaid at each radial position between the first and second plateaus. Traditional JWL's model LX-14 and LX-04 within accuracy, but not so for LX-17. The spall may be partly modeled using the pmin model but high resolution zoning is required. At longer times, …

Date: April 16, 1998

Creator: Anderson, S; Avara, R; Fried, L; Janzen, J; McGuire, E; Souers, P C et al.

Object Type: Report

System: The UNT Digital Library